This invention relates to protection from shock and vibration, and in particular, to apparatus for protection of objects from damage resulting from seismic activity such as earthquakes. The invention is of particular significance to the protection of large art objects and antiquities of museum quality.
A variety of configurations have been utilized in the past for protection from damage due to earthquake. In one approach the structure is designed to be exceedingly strong so that the structure and its support, such as a single object or entire building, moves with the earth movement without damage. Another approach has been to support the object on some type of apparatus so that the object remains essentially fixed while the earth moves, with the object ultimately being restored to its original relationship with the earth. Structures of this nature are shown in U.S. Pat. Nos. 4,496,130; 4,596,373; and 4,801,122; and in Italian patent 639,666. A variation utilizing cables and springs for controlling motion is shown in U.S. Pat. Nos. 4,371,143; 4,402,483; 4,565,039; 4,577,826; 4,617,769; and 4,662,133.
While these prior designs have been satisfactory for some situations, problems are encountered in other arrangements and installations, and it is an object of the present invention to provide a new and improved isolator construction.
In the case of art objects and antiquities many times they are inherently weak or have been weakened over time and often are unstable.
One of the advantages of the isolator of the present invention is the ability to tune the return mechanism so that the natural frequency of the system can be adjusted for each particular object or circumstance. Long period motions may be attenuated by the very large displacement capacity and in addition, vertical accelerations may be controlled with the rigid locking to eliminate chatter. Other advantages include a lower profile and very little maintenance required.